The separation of biological molecules such as proteins, peptides and glycoproteins is performed by gel electrophoresis. The gels, in which the molecules are embedded after electrophoresis, are stained with coomassie-blue dye to visualize the protein bands. After staining of the protein bands, the excess dye is removed by washing the gel repeatedly with de-stain solution. The present invention presents a novel method for both staining electrophoresis gels, as well as removing the background dye during de-staining. Furthermore, a novel method for the quantitative determination of protein concentration in solution is also presented.